ESP Vintage Series year?

I just purchased a surf green ESP Vintage Series Strat style. There's lots of info on the Vintage Plus but I can't find anything on the Vintage series. The only numbers are on the neck plate: 18214 Any knowledge of this model out there?

I belive these were made around 1990 - 1991 after the 400 series but just before the traditional series, I don't have any proof of this, its just a guess. It looks a lot like a 400 series. Does it have large xj frets or small vintage frets?